1. Field of the Invention
This invention relates to radiation curable diluents which are lower alkyl ether (alkoxy) acrylates and methacrylates of particular alkoxylated and non-alkoxylated polyols and to radiation curable compositions containing same.
2. Description of the Prior Art
Radiation curable or hardenable compositions, particularly for coating applications, are known in the art. In view of the restrictions on solvent content in the atmosphere, increasing efforts have been made to provide completely polymerizable systems which do not contain any volatile components, but instead consists of constituents which form either the whole or a part of the hardened film itself.
Although radiation curable oligomers and polymers form the backbone of a radiation curable coating, they cannot normally be used alone because of their high viscosity and poor application properties. Viscosity reduction is usually accomplished by use of reactive monomers. These not only act as diluents for the system, but also copolymerize with the oligomers and polymers and contribute to the final properties of the cured film. Examples of reactive monomers, also referred to as radiation curable diluents, are multifunctional acrylates and methacrylates of alkoxylated and non-alkoxylated polyols. Reference is made to the following U.S. patents for examples of same.
U.S. Pat. No. 3,594,410--Cohen et al, Jul. 20, 1971 PA0 U.S. Pat. No. 3,857,822--Frass, Dec. 31, 1974 PA0 U.S. Pat. No. 4,058,443--Murata et al, Nov. 15, 1977 PA0 U.S. Pat. No. 4,088,498--Faust, May 9, 1978 PA0 U.S. Pat. No. 4,177,074--Proskow, Dec. 4, 1979 PA0 U.S. Pat. No. 4,179,478--Rosenkranz et al, Dec. 18, 1979 PA0 U.S. Pat. No. 4,180,474--Schuster et al, Dec. 25, 1979 PA0 U.S. Pat. No. 4,382,135--Sinka et al, May 3, 1983 PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 -- or mixtures PA0 R"'=H--, CH.sub.3 -- or mixtures PA0 a=1, 2 or 3 PA0 m=0 to about 6 PA0 n=0 to about 6 with the proviso m+n does not exceed about 6, and with the proviso when C.sub.5 is linear, m+n is about 1 to about 6 PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 -- or mixtures PA0 R"'=H-- or CH.sub.3 -- PA0 R""=H-- or CH.sub.3 -- or mixtures PA0 a=1 PA0 m=0 to about 6 PA0 n=0 to about 6 PA0 m+n=0 to about 6 PA0 mono-methoxy trimethylolpropane diacrylate PA0 mono-methoxy, ethoxylated trimethylol propane diacrylate having an average of three moles of ethylene oxide PA0 mono-methoxy, propoxylated trimethylol propane diacrylate having an average of three moles of propylene oxide PA0 mono-methoxy 1,6-hexanediol monoacrylate PA0 mono-methoxy pentaerythritol triacrylate PA0 mono-methoxy, propoxylated pentaerythritol triacrylate having an average of four moles of propylene oxide PA0 mono-methoxy neopentyl glycol monoacrylate PA0 mono-methoxy, ethoxylated neopentyl glycol monoacrylate having an average of two moles of ethylene oxide PA0 mono-methoxy, propoxylated neopentyl glycol monoacrylate having an average of two moles of propylene oxide PA0 mono-methoxy trans-1,4-cyclohexane dimethylol monoacrylate PA0 mono-methoxy propoxylated glycerol diacrylate having an average of three moles of propylene oxide PA0 mono-methoxy propoxylated hexane glycol monoacrylate having an average of two moles of propylene oxide PA0 mono-methoxy 2,2,4-trimethyl 1,3-pentane diol monoacrylate PA0 mono-methoxy ethoxylated 2,2-bis(p-hydroxyphenyl)propane monoacrylate having an average of four moles of ethylene oxide PA0 mono-methoxy bis(p-hydroxyphenyl)methane monoacrylate PA0 mono-methoxy trimethylolpropane dimethacrylate PA0 mono-methoxy, ethoxylated trimethylol propane dimethacrylate having an average of three moles of ethylene oxide PA0 mono-methoxy, propoxylated trimethylol propane dimethacrylate having an average of three moles of propylene oxide PA0 mono-methoxy 1,6-hexanediol monomethacrylate PA0 mono-methoxy pentaerythritol trimethacrylate PA0 mono-methoxy, propoxylated pantaerythritol trimethacrylate having an average of four moles of propylene oxide PA0 mono-methoxy neopentyl glycol monometharylate PA0 mono-methoxy, ethoxylated neopentyl glycol monomethacrylate having an average of two moles of ethylene oxide PA0 mono-methoxy, propoxylated neopentyl glycol monomethacrylate having an average of two moles of propylene oxide PA0 mono-methoxy trans-1,4-cyclohexane dimethylol monomethacrylate PA0 mono-methoxy propoxylated glycerol dimethacrylate having an average of three moles of propylene oxide PA0 mono-methoxy propoxylated hexane glycol monomethacrylate having an average of two moles of propylene oxide PA0 mono-methoxy 2,2,4-trimethyl 1,3-pentane diol monomethacrylate PA0 mono-methoxy ethoxylated 2,2-bis(p-hydroxyphenyl)propane monomethacrylate having an average of four moles of ethylene oxide PA0 mono-methoxy bis(p-hydroxyphenyl)methane monomethacrylate PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 -- or mixtures PA0 R"'=H--, CH.sub.3 --or mixtures PA0 a=1 PA0 m=0 to about 6 PA0 n=0 to about 6 PA0 m+n=0 to 6 PA0 mono-propoxy ethylene glycol monoacrylate PA0 mono-n-butoxy ethylene glycol monoacrylate PA0 mono-methoxy diethylene glycol monoacrylate PA0 mono-ethoxy diethylene glycol monoacrylate PA0 mono-n-butoxy diethylene glycol monoacrylate PA0 mono-methoxy triethylene glycol monoacrylate PA0 mono-methoxy propylene glycol monoacrylate PA0 mono-methoxy tripropylene glycol monoacrylate PA0 mono-propoxy ethylene glycol monoacrylate PA0 mono-n-butoxy ethylene glycol monoacrylate PA0 mono-methoxy diethylene glycol monoacrylate PA0 mono-ethoxy diethylene glycol monoacrylate PA0 mono-n-butoxy diethylene glycol monoacrylate PA0 mono-methoxy triethylene glycol monoacrylate PA0 mono-methoxy propylene glycol monoacrylate PA0 mono-methoxy tripropylene glycol monoacrylate PA0 R'=at least one of C.sub.1 to C.sub.6 PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 -- or mixtures PA0 R"'=H--, CH.sub.3 or mixtures PA0 a=1, 2 or 3 PA0 m=0 to about 6 PA0 n=0 to about 6 and with the proviso m+n does not exceed about 6 PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 -- or mixtures PA0 a=1, 2 or 3 PA0 m=0 to about 6 PA0 m=0 to about 6 and when m+n=0, a=1 with the proviso m+n does not exceed about 6 and with the proviso when C.sub.5 is linear, m+n is about 1 to about 6 PA0 R"=H--, CH.sub.3 --, CH.sub.3 CH.sub.2 --or mixtures PA0 R"'=H-- or CH.sub.3 -- PA0 a=1 PA0 m=0 to about 6 PA0 n=0 to about 6 with the proviso m+n=0 to about 6 PA0 mono-methyl ether of propoxylated pentaerythritol having an average of about four moles of propylene oxide PA0 mono-methyl ether of ethoxylated trimethylolpropane having an average of three moles of ethylene oxide PA0 mono-methyl ether of propoxylated trimethylolpropane having an average of three moles of propylene oxide PA0 mono-methyl ether of 1,6-hexanediol PA0 mono-methyl ether of neopentyl glycol PA0 mono-methyl ether of ethoxylated neopentyl glycol having an average of about two moles of ethylene oxide PA0 mono-methyl ether of propoxylated neopentyl glycol having an average of two moles of propylene oxide PA0 mono-methyl ether of propoxylated glycol having an average of three moles of propylene oxide PA0 mono-methyl ether of trans-1,4-cyclohexanedimethanol PA0 mono-methyl ether of 2,2-bis(p-hydroxyphenyl)propane having an average of four moles of ethylene oxide PA0 mono-methyl ether of bis(p-hydroxyphenyl)methane PA0 mono-methyl ether of 2,2,4-trimethyl-1,3 pentane diol PA0 G=Good--no marking of film PA0 F=Fair--slight marking PA0 P=Poor--penetration and tearing of film PA0 G=Good--85-100% PA0 F=Fair--less than 85%
Conventional multifunctional acrylates and methacrylates such as trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate and 1,6-hexanediol diacrylate and dimethacrylate were the major reactive monomers developed and introduced in the 1970's for use in radiation curable coatings. Although they exhibited several of the desired characteristics of an ideal monomer, there were many problems and limitations associated with their use.
Trifunctional types, e.g., trimethylolpropane triacrylate and pentaerythritol and triacrylate, were fast curing but produced brittle films with severe shrinkage and poor adhesion to a variety of substrates. Moreover, their higher intrinsic viscosities contributed to poorer solvency and inadequate viscosity reduction characteristics which limited their use in many applications. Difunctional types, e.g., 1,6-hexanediol diacrylate and dimethacrylate exhibited superior viscosity reduction but poor or slower cure response. Many of these monomers also posed serious skin irritancy problems in compounding and processing of the coatings.
Thus, a need was shown for reactive monomers with fast cure response (high reactivity), low intrinsic viscosity, low shrinkage and excellent solvating or viscosity reducing properties.